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authorAnton Blanchard <anton@samba.org>2012-01-09 14:29:15 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-01-11 11:54:20 +1100
commita5ccfee05a439b803640e94584056204501db31c (patch)
tree2545bab092fe62924d5ccba8920c137b1e771ba6 /arch/powerpc/kernel/idle.c
parent7b3480f8b701170c046e1ed362946f5f0d005e13 (diff)
downloadtalos-op-linux-a5ccfee05a439b803640e94584056204501db31c.tar.gz
talos-op-linux-a5ccfee05a439b803640e94584056204501db31c.zip
powerpc: Fix RCU idle and hcall tracing
Tracepoints should not be called inside an rcu_idle_enter/rcu_idle_exit region. Since pSeries calls H_CEDE in the idle loop, we were violating this rule. commit a7b152d5342c (powerpc: Tell RCU about idle after hcall tracing) tried to work around it by delaying the rcu_idle_enter until after we called the hcall tracepoint, but there are a number of issues with it. The hcall tracepoint trampoline code is called conditionally when the tracepoint is enabled. If the tracepoint is not enabled we never call rcu_idle_enter. The idle_uses_rcu check was also done at compile time which breaks multiplatform builds. The simple fix is to avoid tracing H_CEDE and rely on other tracepoints and the hypervisor dispatch trace log to work out if we called H_CEDE. This fixes a hang during boot on pSeries. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/idle.c')
-rw-r--r--arch/powerpc/kernel/idle.c12
1 files changed, 2 insertions, 10 deletions
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 7c66ce13da89..0a48bf5db6c8 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -50,12 +50,6 @@ static int __init powersave_off(char *arg)
}
__setup("powersave=off", powersave_off);
-#if defined(CONFIG_PPC_PSERIES) && defined(CONFIG_TRACEPOINTS)
-static const bool idle_uses_rcu = 1;
-#else
-static const bool idle_uses_rcu;
-#endif
-
/*
* The body of the idle task.
*/
@@ -67,8 +61,7 @@ void cpu_idle(void)
set_thread_flag(TIF_POLLING_NRFLAG);
while (1) {
tick_nohz_idle_enter();
- if (!idle_uses_rcu)
- rcu_idle_enter();
+ rcu_idle_enter();
while (!need_resched() && !cpu_should_die()) {
ppc64_runlatch_off();
@@ -106,8 +99,7 @@ void cpu_idle(void)
HMT_medium();
ppc64_runlatch_on();
- if (!idle_uses_rcu)
- rcu_idle_exit();
+ rcu_idle_exit();
tick_nohz_idle_exit();
preempt_enable_no_resched();
if (cpu_should_die())
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